Okay, so this puts the "changed to keep the HGSS/DP relation secret" theory as being quite plausible. The HGSS games were announced in May of 2009 for a September release (in Japan), given the development cycle of the games there was plenty of time for Kusaka to be aware of the game's existence as he was putting together Volume 30 (which was released in Dec 2008).
Unless otherwise stated, I don't see why we can't concur with the magazine run in saying that DPPt one year ahead of HGSS...
...Okay, I can see where the "one-year" theory can be a problem. I'll do a little thinking and revisit this later.
Lol yeah I don't think "time passes" translates as three years. Maybe a few weeks/months, one year at the max, but definitely not three years.
And huh I never knew about the one-year passing hint on the magazines. One year is definitely better than three years imo. I thought it was three years because someone pointed out that Dia/Pearl (forgot who it was) saw the Red Gyarados at the Lake of Rage when he was four eight years ago. But then again it's not like there's only one Red Gyarados in existence. Or it could also mean that the Red Gyarados was around for quite a while before Silver captured it and it wasn't among the masses of Magikarp being forced to evolve. And it was a part of a comedy so I'm not sure to what extent we can take that claim seriously.